This prospective observational study included 140 singleton pregnancies that underwent cervical cerclage at Cam and Sakura City Hospital. The study was approved by the Ethics Committee of Cam and Sakura City Hospital (KAEK/2022.06.180), and written informed consent was obtained from all participants in accordance with the Declaration of Helsinki.
Patients were stratified into three groups based on the clinical indication for cerclage:
Prophylactic cerclage (Group 1, n = 39): A history-indicated cerclage was performed between 12 and 14 weeks of gestation in women with previous painless second-trimester losses due to cervical insufficiency, in the absence of current cervical changes.
Ultrasound-based cerclage (Group 2, n = 62): An ultrasound-based cerclage was performed before 24 weeks for cervical length < 25 mm in women with a history of preterm birth before 34 weeks, or < 20 mm in those without such history.
Rescue cerclage (Group 3, n = 39): Emergency cerclage performed in cases of premature cervical dilatation with prolapse of fetal membranes into the vagina, typically performed up to 24 weeks of gestation.
Inclusion criteria comprised singleton pregnancies between 18 and 45 years of age with documented indication for cervical cerclage and provision of informed consent.
Exclusion criteria included chronic maternal diseases such as hypertension, cardiac disease, or diabetes mellitus; fetal aneuploidy or major structural malformations; prior cervical surgery; multiple pregnancies; smoking; cervicitis; and history of preeclampsia, intrauterine growth restriction, or small for gestational age delivery in previous pregnancies.
All cerclages were performed by one maternal-fetal medicine specialist using the McDonald technique under regional or general anesthesia. Following placement of ring forceps on the anterior and posterior cervical lips, cervical length and dilatation status were assessed. A suture was placed using either Prolene No. 1 or Mersilene tape, positioned as posteriorly as possible starting from the 12 or 1 o’clock position while carefully avoiding vascular structures at the 3 and 9 o’clock positions. After appropriate suture tightening and confirmation of cervical closure, hemostasis and suture integrity were verified.
Perioperative management included a single preoperative intravenous dose of cefazolin (1 g) and indomethacin, followed by daily vaginal progesterone (200 mg); bed rest was recommended for 24 h before resumption of light activity.
Comprehensive demographic and clinical data were systematically recorded, including maternal age, gravidity, parity, body mass index, preoperative and postoperative cervical length measurements, gestational age at cerclage, and birth outcomes including gestational age at delivery and birth weight. Small for Gestational Age (SGA) was defined as a birth weight below the 10th percentile for gestational age, while Intrauterine Growth Restriction (IUGR) was defined as pathologic fetal growth restriction with an estimated fetal weight (EFW) or abdominal circumference (AC) below the 10th percentile, accompanied by abnormal Doppler findings or other evidence of fetal compromise. In this study, all SGA cases were classified based solely on this weight criterion regardless of IUGR status, allowing us to evaluate the association between uterine artery Doppler changes and SGA. Definitions were based on ACOG Practice Bulletin No. 227 (2021)13 and ISUOG Practice Guidelines (2020)14.
Uterine artery Doppler evaluations were performed preoperatively, immediately postoperatively, and at 6 weeks by a single maternal-fetal medicine physician using standardized technique and identical equipment (Hitachi Aloka Arietta 70).
A transabdominal 3.5–5 MHz probe was used with the patient supine and bladder moderately filled. Uterine arteries were assessed distal to the internal cervical os near the iliac junction. Doppler angle was kept < 60°, and ≥ 3 consecutive high-quality waveforms were obtained for each artery. Mean PI was calculated from bilateral measurements to minimize variability.
At our institution, first-trimester preeclampsia screening routinely involves uterine artery Doppler assessment; aspirin prophylaxis (100 mg/day) is initiated when the uterine artery pulsatility index (PI) exceeds the 95th percentile. In this study cohort, no patients met this criterion, and none received aspirin.
Data were analysed using R version 4.3.1 (R Foundation for Statistical Computing, Vienna, Austria). Descriptive statistics are presented as mean ± standard deviation (SD) for normally distributed continuous variables and as median (interquartile range) for non-normally distributed variables. Categorical variables are summarised as counts and percentages. Normality was evaluated with the Shapiro–Wilk test and by visual inspection of Q–Q plots. When the normality assumption was violated, non-parametric tests were applied: the Wilcoxon signed-rank test for paired comparisons (e.g. pre- and postoperative uterine-artery pulsatility index [PI]) and the Mann–Whitney U test for independent samples. Differences in PI between (i) pre- and postoperative measurements and (ii) postoperative and 6-week follow-up measurements were assessed within each indication group. Categorical data were compared with the χ² test or Fisher’s exact test, as appropriate. Statistical significance was defined as P < 0.05.
A post-hoc power analysis was performed to evaluate the ability of the study to detect the observed change in uterine-artery PI before and after cerclage placement. Although the paired comparison employed the Wilcoxon signed-rank test because the data were non-normal, power was conservatively approximated with a paired-samples t-test model. With a sample size of 140, an α level of 0.05, and an observed mean difference of 0.08 (SD ≈ 0.48), the study had > 90% power to detect this difference. Calculations were performed using G*Power version 3.1.9.7.